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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Usable Stops of Dynamic Range

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Ryan Emanuel

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How many EV stops are you guys getting between the purple noise floor and the red clipping ceiling in false color on the scarlet. In redlogfilm at 320 iso I'm getting 3.5 stops above middle grey and 5.5 stops below. In redlogfilm at 800 iso I'm getting 4.5 below middle grey and 4.5 above. Are you guys getting similar results?

I was also under the impression of 12 usable stops, I would love some input on this. Most likely I'm doing something wrong
 
The "purple" is conservative. It says - there may be noise down here, be careful before you place majorly important image detail in this region. It doesn't mean "image in purple region is un-usable so avoid."

Graeme
 
Josh Beadle said:
Try this:

http://www.youtube.com/watch?v=_7SZ58CugpY

Did for my Canon's - never used for a Cine camera . . . but it can be done since a still frame is a still frame regardless how it's captured. DMSC and all you know
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thats how i got my initial results using that software, then I got the same results by finding middle grey on a grey card with the exposure filter function and moving down stop by stop until I clipped the noise floor and up stop by stop until I hit the highlight ceiling in false color. I just wanted to see if people were getting similar dynamic range on their scarlets. Or I guess another question to ask is when the scarlet is advertised as have 13.5 stops of dynamic range is that measured in EV stops or is it some thing different, if it is different that how many usable EV stops are there, because I'm getting around 10 EV stops in Redlogfilm
 
Graeme Nattress said:
The "purple" is conservative. It says - there may be noise down here, be careful before you place majorly important image detail in this region. It doesn't mean "image in purple region is un-usable so avoid."

Graeme
Click to expand...

Thanks Graeme, but is it safe to assume that the red is clipped zero information?
 
The clipping point, being more easily defined is showing proper clipping - there's not much wiggle room in there.

Graeme
 
Yes, that sounds about right.

Graeme
 
Ahhhhh.... but where does one place middle grey in the exposure........ ;)

Graeme, this goes back to our conversation about ISO. I did some real proper testing today, i have to admit, the RED impressed the shit out of me. My DIT and i built a workflow that gave us everything the MX has to offer, and it made me rethink what i can use the S-X for. :)

SOooooo glad i bought a RED.
 
Timur Civan said:
Ahhhhh.... but where does one place middle grey in the exposure........ ;)

Graeme, this goes back to our conversation about ISO. I did some real proper testing today, i have to admit, the RED impressed the shit out of me. My DIT and i built a workflow that gave us everything the MX has to offer, and it made me rethink what i can use the S-X for. :)

SOooooo glad i bought a RED.
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Care to share ?
 
Where do you place mid grey indeed.... There's lots of room for user-choice here, and nothing fixed in stone about where. Always happy to work through stuff with you Timur.

Graeme
 
Graeme Nattress said:
Where do you place mid grey indeed.... There's lots of room for user-choice here, and nothing fixed in stone about where. Always happy to work through stuff with you Timur.

Graeme
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Well, that's exactly what makes the RED cams so good to work with, you can put it in such a huge range, and still come home with a nice and rich image. Especially so with the Epic.

ISO and digital cams... That's another story :)
 
That's just it. Let's not burn in anything to the image that we can avoid burning in.

Graeme
 
If you have the possibility to do serious grading, I'd follow the ETTR rule: Expose To The Right, since clipping is a hard edge. Simply avoid any clipping of areas that should not be blown out.

But noise is a soft border, influenced by the ratio between shooting and presentation resolution and the possibilities of noise reduction. If you shoot 4K, but it's meant for HDTV, you will loose quite some noise in downscaling. Plus, really good noise filters in post can get you another full stop or 1.5. The rest is taste and purpose.

It all comes down to the fact that a grey card is not the only (and maybe not the best) measure any more. You may rather want to check your scene contrast, and in extreme cases you may decide to go HDRx.
 
Thanks for the input guys. If I'm understanding correctly altering the black, toe, mid, knee, and white points in a customized curve will yield better results in different situations. Does anyone have any suggestions on where to place points of the curve to retain more stops of highlights, balanced stops in the highlights and darks, or more stops in the darks?
 
Ryan Emanuel said:
Thanks for the input guys. If I'm understanding correctly altering the black, toe, mid, knee, and white points in a customized curve will yield better results in different situations. Does anyone have any suggestions on where to place points of the curve to retain more stops of highlights, balanced stops in the highlights and darks, or more stops in the darks?
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Hm... That was a strange question, really...

You need to start off by having the full latitude avaiable. best purely technical startingpoint for that would be redlogfilm or linear light at 320 (or less if your wb is off senter).

But you know what? For most images that is really a bad advice these days, especially if you are not used to or don't have the tools for linear or log grading.

Best advice, methinks, is to start off with RG2 or 3 and RC3, and for the images where you think the highlighta are clipped or the lowlights are crushed, you could try to start from the log or lin space at 320. Your lin/log grade should be at least as good as your RedGamma3 grade for it to make sense...
 
Gunleik Groven said:
Hm... That was a strange question, really...

You need to start off by having the full latitude avaiable. best purely technical startingpoint for that would be redlogfilm or linear light at 320 (or less if your wb is off senter).

But you know what? For most images that is really a bad advice these days, especially if you are not used to or don't have the tools for linear or log grading.

Best advice, methinks, is to start off with RG2 or 3 and RC3, and for the images where you think the highlighta are clipped or the lowlights are crushed, you could try to start from the log or lin space at 320. Your lin/log grade should be at least as good as your RedGamma3 grade for it to make sense...
Click to expand...

Maybe I should rephrase, I'm trying to understand the limits of the camera as far as dynamic range in a measurable medium. The OP was my not precise findings. I saw above that Timur and Graeme hinted that where you set exposure for middle grey will shift stops in your dynamic range. What I wanted to know was at what IRE are people exposing middle grey and are they getting more than 4.5 stops between middle grey and clipped highlights.
 
Ryan Emanuel said:
Maybe I should rephrase, I'm trying to understand the limits of the camera as far as dynamic range in a measurable medium. The OP was my not precise findings. I saw above that Timur and Graeme hinted that where you set exposure for middle grey will shift stops in your dynamic range. What I wanted to know was at what IRE are people exposing middle grey and are they getting more than 4.5 stops between middle grey and clipped highlights.
Click to expand...

Ah, now I understand! :)

Read this:
http://www.gunleik.com/tests/alexmx/RED1_MX_and_Arri_Alexa/ISO_&_Kelvin_-_an_introduction.html
 
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